The objective of the proposed research is to evelop reagentless, solid-sueface fluorescence monitoring methods for the assay of enzymes and substrates of clinical significance (cholinesterase, urea, glucose, alkaline phosphatase, lipase, lactate dehydrogenase, GOT, GPT, etc.). A reaction rate between an enzyme reactant and a substrate reactant is fluorometrically measured by forming a solid reactant film of one of the reactants on a silicone matrix pad. The reactant film is then contacted with a solution of the other reactant to produce a fluorescent material; the change of fluorescence with time is measured by placing the pad in a fluorometer and comparing the rate of change of fluorescence against a calibration curve to determine the concentration of the reactant in solution.